[unreadable] Modem cardiac surgical practice involves the routine use of cardiopulmonary bypass (CPB) for performing both coronary artery bypass graft (CABG) procedures on the heart surface as well as procedures inside the heart, classified broadly as intracardiac surgery. However, recent studies indicate that CPB carries important risks that can lead to reduced neuropsychiatric function and stroke in adults, and neurodevelopmental deficits with impaired fine motor skills in children. Other adverse effects of CPB include activation of inflammatory mediators and the complement cascade, showers of particulate emboli with aortic manipulation and crossclamp release, and air embolus. To avoid these risks of CPB, several investigators have begun to evaluate the results of CABG procedures performed without CPB. Early results of these "beating heart" procedures indicate equivalent patency rates, comparable mortality rates, and significant savings. Development of techniques for intracardiac beating heart surgery, however, must overcome the unique challenge of the inability to image the anatomic features of the heart with sufficient detail and time resolution to permit instrument navigation and precise tissue manipulation. Real time 3D echo has the potential for overcoming these issues thereby enabling intracardiac beating heart surgery. The overall aim of this proposal is to adapt real time 3-D ultrasound imaging specifically for image-guided interventions and integrate this technology with safety measures through instrument tracking, tactile sensing, and acoustic tissue analysis to permit safe and accurate intracardiac beating heart surgery. The complexity of this problem is well suited to a BRP approach. The PI has assembled a multidisciplinary team and established a unique partnership among industry-based engineers (Philips Medical Systems), university-based engineers (Harvard University; Boston University), and clinical investigators (Children's Hospital; Brigham and Women's Hospital). Together, we will approach this problem by addressing the following specific aims: AIM I: Modify real-time 3-D ultrasound to optimize image presentation for guiding intracardiac surgical procedures in a beating heart. AIM II: Adapt high-resolution electromagnetic tracking equipment for precise intracardiac navigation and modify surgical instruments to limit interference with ultrasound imaging during beating heart surgical procedures. AIM III: Develop instruments to provide both tactile sensing and acoustic tissue analysis for increased procedure safety. AIM IV: Integrate real time 3-D ultrasound imaging and tracking equipment with computer-enhanced instrument control for improved task performance and safety during image-guided surgery. [unreadable] [unreadable]